Cord lock



ZESELJH Jam. 17, 1956 H. K. LORENTZEN CORD LOCK Filed Dec. 6, 1954 INVENTOR HAN5 K. LORENTZEN ATTORNEYS United States Patent CORD LOCK Hans K. Lorentzen, Montclair, N. J., assignor to Lorentzen Hardware Mfg. Corp., New York, N. Y., a corporation of New York Application December 6, 1954, Serial No. 473,279

7 Claims. (Cl. 188-64) This invention relates to a cord lock that is used for selectively locking and releasing the two lift cords of a curtain that is raised and lowered by the simultaneous equal movement of two such cords. The term curtain is used herein in its broad sense of a hanging device which blocks or obscures the view, as for example, the view through a window. In many installations a continuous length of cord is used, being doubled back upon itself to form two branches, each of which acts as a lift cord for the curtain.

Two specific types of curtains which are customarily raised and lowered by two lift cords are porch shades and Venetian blinds. A porch shade is in the nature of a hanging mat and is often made with thin strips of wood or bamboo which are flexibly held in edge-to-edge relation by interlaced strings that act as warp. It and similar shades may be raised by rolling the shade upwardly under the action of two lift cords which are looped under the bottom edge of the shade. in a Venetian blind, the two lif cords pull the bottom bar of the blind upwardly, and the bottom bar picks up the slats one after the other.

The two lift cords are customarily reeved to exert their raising and lowering action at the bottom of the curtain near the two vertical edgesthereof, respectively. Accordingly, the two lift cords must move in unison to keep the bottom of the curtain horizontal as the curtain is raised and lowered. It is common practice to connect the two lift cords together with an equalizer, which is usually located some distance below the head bar of the curtain but above the point where the two cords are grasped and pulled downwardly by the operator to raise the curtain. The use of such equalizer tends to insure equal travel of the lift cords during the raising of the curtain.

In lowering the curtain from raised position to an intermediate position, the cord equalizer may remain below the hands of the operator and, therefore, not come into play. Further, even if the equalizer does come into play, the operator must release the tension on the cords as they are locked by the cord lock; and unless the cord lock, which is usually located at the top of the curtain, brings both cords to a stop after an equal amount of travel during the locking operation, the curtain will not be maintained horizontal. For example, if the cord lock'securely engages one cord but allows the other cord to travel further, the bottom of the curtain will come to rest in a noticeably tipped position, which is obviously undesirable.

A variety of conditions may cause conventional cord locks to engage the two lift cords in different manners so that one is locked while the other slides therethrough to some extent. Cord such as is used for lift cords cannot be relied upon to be of precisely uniform diameter throughout its length. Thus, small but significant variations in the diameters of the two lift cords may occur at the point where the cord lock engages them. Further, the cord-guiding means of the cord lock may fail to present the two lift cords symmetrically to the locking dog,

2,731,111 Patented Jan. 17, 1956 which dog spans the two side-by-side lift cords and presses them against the cord-guiding surface.

Among the objects of the present invention are to provide a cord lock for the lift cords of a curtain which uniformly engages both lift cords to lock the same, regardless of usual variations in diameter of the lift cords or of usual variations in the manner of presentation of the two lift cords to the dog; to provide such a cord lock of simple, rugged construction having a cord-lock dog which may conveniently be made by being stamped and bent from sheet metal; to provide, in a specific embodiment thereof, a cord lock of the above-indicated type for use in Venetian blinds of the enclosed-head type; and generally to improve cord locks for locking two cords simultaneously.

Further objects and objects relating to details and economies of construction, operation, and use will more definitely appear from the detailed description to follow:

My invention is clearly defined in the appended claims. In the claims, as well as in the description, parts may at times be identified by specific names for clarity and con venience, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention is illustrated in the accompanying drawings forming part of this specification, in which:

Fig. l is a fragmentary isometric view of a Venetian blind of the enclosed-head type incorporating a cord lock embodying the present invention, the blind being broken through above the bottom bar and some of the slats of the blind being omitted, and a part of the head channel being broken away to show the cord lock.

Fig. 2 is an end elevation of the cord lock of Fig. l, viewed from the right as it appears in Fig. 1.

Fig. 3 is a view in section through the cord lock of Figs. 1 and 2 taken generally along the line 3-3 of Fig. 2, the locking dog of the cord lock being shown disengaged from the lift cords to permit travel of the cords for lowering the blind.

Fig. 4 is a view in vertical section through the cord lock similar to Fi g. 3 but with the dog lockingly engaging the lift cords.

Fig. 5 is a section through the cord lock taken generally along the line 5-5 of Fig. 4, a part of the cord-locksupporting flange being broken away, and the dog being in cord-engaging position.

Fig. 6 is an isometric view of the locking dog shown in Figs. 3, 4, and 5.

Fig. 7 is a plane development of the locking dog shown in Figs. 3 through 6.

Referring now to the drawings, the Venetian blind 5 of Fig. l, which is of the simple-lift variety, has a head bar 10, a bottom bar 14, and slats 13, the bottom bar and the slats being supported by ladder tapes, one of which is .shown at 11. The lift cords 15, 15, formed as two branches of a long cord that is doubled back on itself to form a loop at 17, are reeved through the cord lock 19, through the head bar, and passed through the slats 13 between the two branches 12, 12. of the ladder tapes ll. (one shown), one lift cord being associated with each ladder tape. In the blind shown, the lift cord 15 is associated with the one ladder tape that is shown in Fig. I, while the lift cord 15 extends along the headbar channel 10 and then vertically between the branches of the ladder tape at the left of the blind (not shown). The free ends of both lift cords are attached to the bottom bar 14.

A lift-cord equalizer, shown generally at 16, connects the cords 15, about three slats below the head bar so that when a person grasps either one or both cords below the equalizer and pulls them downwardly, the

cords 15, .15 travel equal distances to raise the bottom bar 14 whereby the bottom .bar is maintained level. As previously explained, there is no other means which connects the lift cords 15, 15 together except for'the bottom bar itself. So long as the operator retains proper control of the travel of cords 15, 15' in the direction to lower the blind, bottom bar 14 remains horizontal. When, however, the operator releases his grasp upon the lift cords with the blind in other than fully lowered position, the only means preventing travel of the cords in a blind-lowering direction is the cord lock 19. The cord lock of the present invention is of such construction that it locks both cords after an equal amount of blindlowering travel during the locking operation, regardless of variations in cord diameter or of the manner of presentation of the cords to the locking dog.

The body of the cord lock shown is somewhat similar to that shown in Nelson United States Patent 2,587,752. Such cord lock is mounted above the hole in the bottom 21 of the head channel so that the cords 15, 15' depending from the cord lock pass freely through the hole. The body or housing 22 of the cord lock is generally of U shape; and it has two opposite generally parallel side walls 24 and 25, with a connecting end wall 26 that forms the bight of the U. The end wall 26 is stamped with an inwardly projecting central rib at 27 which extends longitudinally of the end wall 26 and forms an abutment for the cord-locking dog when the latter is in cord-locking position, as will be explained later. The upper free corners of side walls 24 and are flared outwardly at 23, 23 to present smooth guiding surfaces above the runs of cords 15, 15' passing over roller 32 (to be described). When the lift cords are manipulated quickly or roughly the tension on the cords may decrease momentarily so that the runs tend to leave the upper surface of the roller. The flared side-wall portions 255, 23 aid in returning the cords to their guiding grooves when normal tension is again restored to the cords.

The cord-lock body 22 has a mounting flange 29 which is generally flat and extends rearwardly from the lower edge of the rear side wall 24 of the cord-lock body. The flange 29, which is mounted upon the upper surface of the bottom 21 of the head channel, makes an acute angle with the sides 24 and 25 of the body so that the cordlock body has the tipped position shown in Figs. 1 and 2. The cord lock is retained upon the head channel by means of upstruck tabs on the bottom of the head channel, such tabs being bent over the ends of flange 29 at notches provided therein. A short vertical leg 30 depends from the lower edge of side 25 of the body and has thereon a narrow forwardly directed flange or foot 31 which rests upon the bottom 21 of the head channel forwardly of the hole 2-9.

The cord housing 22 supports means mounted thereon presenting a guiding surface extending between the side walls of the housing and receiving the cords in side-byside position. In the cord lock shown, a headed pintle pin 34 extends through the side walls 24 and 25 of the cord-lock body and carries the freely rotatable lift-cordguiding roller or pulley 32. Member 32, as shown, is provided with two shallow grooves to guide the lift cords 15, 15 in parallel, side-by-side relationship thereover from the vertical runs thereof leading from the loop 17 to the generally horizontal runs extending longitudinally of the head channel. The side walls 24 and 25 of the cord-lock body act as cord-guiding means to tend to retain the cords in the grooves on roller 32. Located to the right of and parallel to the pintle pin 34, and relatively close to the end wall 26 of the cord-lock body, is a second pintle pin 36 which loosely pivotally mounts the cord-locking dog 35.

The cord-locking dog 35, shown in detail in Fig. 6, is of generally U shape, and has a short finger 37 having cord-engaging teeth 39 on-the free 'end thereof and a long finger 40 parallel to the short finger and having similar teeth 41'on its free end. The bight of the dog 35 is generally part cylindrical, the inner surface thereof forming a portion of a substantially circumferentially closed journal 38 loosely receiving the pintle pin 36. Such journal is completed by short portions of fingers 37 and 40 and the transversely extending tabs 45, 45 which, in this instance, are integral with the short finger 37. The dog has a width somewhat less than the distance between side walls 24 and 25 of the cord-lock body, which walls act to limit sidewise movement of the dog. However, the dog is sufliciently wide to span both lift cords on roller 32.

The rear surface 42 of the bight 4- of the dog is generally part cylindrical. The dog 35 hangs loosely upon the pintle pin 36 when the dog is in cord-released position, away from the cord-guiding roller 32 as shown in Fig. 3. The terminal cord-released position of the dog is determined by the inwardly bent tab 46 which depends from the lower end of the rib 27.

The cord lock shown is of a type that has been referred to in the trade as crash-proof, meaning thereby that it automatically engages the lift cords to prevent appreciable lowering of the blind if the operator simply releases his grasp upon the cords- When the cords are thus released and the blind starts to fall, the inherent stiffness of the cords causes them to swing to the right and engage the short finger 37 of the locking dog 35. The dog thereupon is turned clockwise into the position shown in Fig. 4 in which it firmly jams the lift cords between the teeth on its two fingers and the guide roller 32.

In the cord-locking position of the dog shown in Fig. 4 the thrust upon the dog urging it to the left against the cords is contributed solely by engagement between the generally part-cylindrical rear bearing surface 42 of the dog and the rib 27. The looseness of fit between the pintle 36 and the journal 38 on the dog, plus the fact that the dog 35 is appreciably narrower than the distance between the inner faces of side walls 24 and 25 of the cordlock body, allows the dog to assume whatever canted position is required to thrust the ends of its fingers against the two lift cords with substantially equal force. Such a canted position of the dog is shown in Fig. 5 wherein the dog is shown in locking engagement with lift cords at a point where the diameters of the cords are unequal. The larger diameter of cord 15' has canted the dog somewhat clockwise, so that the teeth on the two fingers, which span the two cords, engage both cords at substantially the same time after release of the lift cords and with substantially the same locking force. Because the rear bearing surface 42 of the dog, which engages abutment rib 27, is rounded, the dog is freely pivotable from the position shown in Fig. 3 to that shown in Fig. 4. The rib 27, being relatively narrow and engaging bearing surface 42 substantially centrally, does not impose an undue restraint upon the canting of the dog. The dog 35 will also be canted, even though the lift cords are of equal diameter, if one of the cords should ride part way out of its groove on roller 32 in the location confronting the dog 35.

The cord lock is released by pulling the lift-cord loop 17 vertically downwardly so that the dog 35 is loosened from the cords and thus falls to the cord-released position of Fig. 3. Such position may be varied as required by altering the angle of the tab 46.

Although the cord lock of the invention has been illustrated in connection with a cord lock of the so-called crash-proof type, it is to be understood that the invention is also applicable to cord locks of the type wherein the depending lift cords must be deliberately swung sidewardly by the operator in order to lock the cords.

I claim:

1. A cord lock for the lift cords of a curtain comprising a housinghaving two generaly parallel side walls and a connecting end wall, means mounted on the housing presentinga cord-guiding surface extending between the side walls, a cord-locking dog loosely pivoted between the side walls of the housing, the dog having a cord-engaging finger, the dog being mounted to rotate said finger generally parallel to the side walls from a cord-locking position in which it confronts the guiding surface and presses the cord thereagainst to a cord-releasing position spaced from said surface, the dog having a rounded bearing portion on the opposite side of its pivotal axis from the finger, an abutment on the end wall of the housing confronting the bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position and an inbent tab on the housing forming a stop for the dog in its cord-releasing position.

2. A crash-proof cord lock for the life cords of a Venetian blind comprising a housing having generally parallel side Walls and a connecting end wall, a roller journalled between the side walls and presenting a peripheral surface for guiding two cords thereover in parallel side-by-side relationship, a cord-locking dog loosely pivoted between the side walls of the housing about an axis generally paralleling and spaced laterally from the surface of the roller, the dog having a finger to span and engage both cords, the dog being mounted to rotate said finger from a cord-locking position in which it confronts the surface of the roller and presses the cords thereagainst to a cord-releasing position spaced from said roller, the side Walls of the housing retaining the cords sidewardly on the surface and limiting sidewise movement and canting of the dog, the dog having a rounded bearing portion disposed on the opposite side of the pivotal axis of the dog from the finger and close to said axis, and an abutment formed as a central inbent longitudinal rib on the end Wall of the housing confronting the central zone of the bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position.

3. A dog for a cord lock for curtains comprising a U- shaped member bent from sheet metal to present generally parallel spaced legs connected by a rounded bight, the inner surface of the bight forming a part of a journal surface for the dog, the outer surface of the bight forming an outer rounded end-bearing surface, and means extending between the legs to form, with the inner surface of the bight, a substantially circumferentially closed pintle-receiving journal.

4. A cord lock for the lift cords of a curtain comprising means presenting a fixedly located cord-guiding surface, a pintle pin fixed with respect to, generally paralleling, and spaced laterally from the surface, a dog comprising a U-shaped member bent from sheet metal to present generally parallel spaced legs connected by a rounded bight, the inner surface of the bight forming a part of a journal surface for the dog, the outer surface of the bight forming an outer rounded end-bearing surface, and means extending between the legs to form, with the inner surface of the bight, a substantially circumferentially closed journal loosely receiving the pintle pin, the dog being mounted to rotate said legs from a cord-locking position in which the free ends of the legs confront the guiding surface and press the cord thereagainst to a cord-releasing position spaced from said surface, and a fixedly positioned abutment substantially narrower than the bearing portion confronting the central part of the end-bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position.

5. A cord lock for the lift cords of a curtain comprising means presenting a fixedly located cord-guiding surface, a loosely pivoted cord-locking dog spaced from said surface, the dog having a cord-engaging finger, the dog being mounted to rotate said finger from a cordlocking position in which it confronts the guiding surface and presses the cord thereagainst to a cord-releasing position spaced from said surface, the dog having a rounded bearing portion disposed on the opposite side of the pivotal axis of the dog from the finger and close to said axis, and an abutment substantially narrower than the bearing portion confronting the central part of the bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position.

6. A cord lock for the lift cords of a curtain comprising a housing having two generally parallel side walls and a connecting end Wall, a cord-guiding roller journalled between the side walls, a cord-locking dog loosely pivoted between the side walls of the housing, the dog having a cord-engaging finger, the dog being mounted to rotate said finger generally parallel to the side walls from a cord-locking position in which it confronts the roller and presses the cord thereagainst to a cord-releasing position spaced from said roller, the dog having a rounded bearing portion on the opposite side of its pivotal axis from the finger, and an abutment on the end wall of the housing confronting the bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position.

7. In a curtain having a pair of lift cords, the combination with said lift cords of a cord lock comprising a support presenting a fixedly located surface for guiding said lift cords thereover in parallel side-by-side relationship, a cord-locking dog loosely pivotally mounted on said support, the dog having a cord-engaging finger, the dog being mounted to rotate said finger from a cord-locking position in which it confronts the guiding surface and presses the cords thereagainst to a cord-releasing position spaced from said surface, the dog having a bearing portion disposed on the opposite side of a pivotal axis of the dog from the finger, and an abutment confronting the bearing portion of the dog and sustaining the thrust on the dog when the dog is in cord-locking position.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,033 Dodge Aug. 24, 1937 2,207,516 La Ganke July 9, 1940 2,552,841 Charbonneau May 15, 1951 

